1. Field of the Invention
This invention relates to a zirconium system amorphous alloy having amorphous-forming ability.
2. Description of the Related Art
Conventionally, it is known that an amorphous alloy has excellent characteristics in terms of magnetic properties, mechanical properties, chemical properties, etc., in comparison with a crystal alloy. Many alloy compositions which can form an amorphous phase such as Fe systems, Ni systems, Co systems, Al systems, Zr systems, and Ti systems, have been developed.
Generally, an amorphous alloy is obtained by rapid cooling of an alloy in molten state. As manufacturing methods of an amorphous alloy, known as various methods such as a single roll method and a dual roll method for obtaining thin sheet, a method in which a thread of molten metal is poured into rotationally flowing cold liquid for obtaining thin wire, an atomizing method and a cavitation method for obtaining alloy powder.
However, most amorphous alloys obtained by these conventional methods are of small mass, and obtaining bulk material is difficult.
Therefore, amorphous alloys having excellent mechanical characteristics are rarely used as structural materials. For this reason, as methods for obtaining large bulk material, a method of extrusion working of amorphous powder having a supercooling liquid area, and a casting method with a copper mold have also been attempted. However, the extrusion working method does not reach for obtaining strength of thin sheet made at a stretch, and there are some drawbacks such as the need for many manufacturing process steps and the need for large manufacturing apparatus. In the casting method, molten metal is successively poured into the copper mold, and cooled surfaces under the melting point of the molten metal are thereby formed into layers. This generates cold shut, amorphous area of the molten metal is crystallized by heat of molten metal supplied later, and the product includes many defects. In addition, the product cannot be used as a bulk material (structural material) due to problems in strength greatly resultant from the defects.
Further, the amorphous state is not necessarily obtained in all alloy compositions, good forming ability of amorphous, mechanical characteristics, etc. are demonstrated in some definite alloy compositions. It has been found by experiments conducted by the inventors of the present invention with repetition of much trial and error, that a composition having the best amorphous characteristics obtained by one manufacturing method does not necessarily correspond to a composition with which the best amorphous is obtained in another manufacturing method.
It is therefore an object of the present invention to provide a zirconium system amorphous alloy which can be produced in bulk and which has excellent strength characteristics, is well-workable, and is usable as structural material.